Adhesion of pathogens to oral surfaces is considered the first step in colonization and initiation of pathological processes in the oral cavity such as caries and periodontal disease. Consequently, oral factors that modulate such activity are of considerable importance to us. The overall objective of our study is to identify factors that modulate the bacterial interaction with oral surfaces and change this interaction to reduce plaque accumulation, and ultimately to minimize caries and periodontal disease formation. Human submandibular/sublingual saliva contains a protein, termed Adhesion- Promoting Protein (APP), that binds and promotes attachment of Streptococcus mutans to enamel surfaces in vitro and thus helps the initial colonization of the tooth that ultimately leads to caries formation. We have purified APP from one individual and raised antibodies to it. This antibody will be used, in the current proposal, to purify additional APP and characterize the protein and subsequently clone and sequence the genes encoding APP. Understanding the nature of this protein and obtaining the full sequence will set the stage to identify the protein segments important in promoting adhesion of Streptococcus mutans to enamel surfaces. This in turn will lead to better ways to prevent plaque accumulation and formation of dental decay with obvious medical and socio-economic benefits.